Recommendation of a Clinical Impulse Response Analysis for Catheter Calibration-Dum** Coefficient and Natural Frequency are Incomplete Parameters for Clinical Evaluation

Abstract

Objects. The dam** coefficient and natural frequency are standard parameters for clinicians to evaluate the dynamic responses of pressure monitoring lines. But in fact, we had experienced some cases in which there were discrepancies between these parameters and frequency response curves. We tried to elucidate the defectiveness of the dum** coefficient and natural frequency with our new catheter calibration methods. Methods and results. At first we made a laboratory study with a function signal generator, a pressure wave converter, two pressure amplifiers and a personal computer. Using with our high-precision frequency response measurement method (step-response analysis) we clearly demonstrated the defectiveness of these parameters. Additionally a more sophisticated original method (clinical impulse response analysis) was also demonstrated in clinical recommendation, which makes it possible to measure true frequency response characteristics (system transfer function) without a function signal generator and a pressure wave converter, even in the operating room just after priming of the monitoring circuit without contamination. Conclusion. We recommend a clinical impulse response analysis for catheter calibration, instead of dum** coefficient and natural frequency.